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Philip J. Riggan

Research Ecologist
Fire and Fuels Program
4955 Canyon Crest Drive
Riverside, CA 92507
United States
Current Research

Dr. Riggan is investigating the spatial patterns and rates of spread and energy release of large fires and effects on large-fire behavior of fire-altered winds, fuel loading and condition, and aerially delivered fire retardant and suppressants. He and his team are developing and applying airborne remote-sensing systems for the quantitative measurement of wildland fires and developing applications for making fire intelligence readily available to and interpretable by incident management teams during ongoing large fires. He is also co-principal investigator on an interagency study that is developing applications of fire observations by new satellite-based sensors, including the Visible Infrared Imaging Radiometer Suite (VIIRS), and is principal investigator for a bilateral research program and interagency working group on fire and environmental change in tropical ecosystems.

Past Research

Dr. Riggan has conducted research on remote measurement of wildfire properties; the biogeochemistry, primary production, plant community development, and effects of fire in Mediterranean ecosystems of California; and the global consequences of wildland fire in tropical ecosystems. He has been Principal Investigator and leader of the Forest Service/IBAMA Working Group on Fire and Environmental Change in Tropical Ecosystems and led eight airborne remote sensing campaigns in Brazil from 1992 through 2000 that made the first synoptic, quanitiative measurements of large wildland fires. He also managed interagency teams studying watershed-scale fires and fire effects on biogeochemistry and the atmosphere in 1984/85 in California and under sponsorship of the Defense Nuclear Agency in California and Canada in 1986 and 1987. Since 2000 he has led development of the FireMapper thermal-imaging radiometer and its application to measurement and monitoring of large wildland fires and forest drought stress and mortality in mixed conifer forest.

Research Interest

fire remote sensing, fire behavior, global consequences of wildland fire in tropical ecosystems

Why This Research Is Important

Wildland fires continue to threaten life, property, natural resources, and ecosystems in the western United States. They are an important global source of greenhouse gas emissions to the atmosphere and can adversely affect air quality in both rural and urban settings for weeks at a time. Management of fires and their impacts requires strategic information, such as long-term changes in fire frequency and behavior or structural changes in ecosystems from burning, and tactical fire intelligence, such as current fire locations, intensity, and rates and direction of spread. Dr. Riggan's research has provided the remote sensing tools and systems to measure the physical properties of large wildland fires, and is providing the first synoptic and high-resolution measurements of fire behavior. His work with the Government of Brazil is estimating the rates and impacts of burning in tropical savanna and forests and seeking solutions to mitigate fire emissions of greenhouse gases and air pollutants with potentially regional or global consequences on climate change and human and ecosystem health.

  • University of Washington, College of Forest Resources, Doctor Of Philosophy, Forest nutrition: measurement and simulation of growth and yield and nitrogen cycling in Douglas-fir forest, 1979
  • San Diego State University, B.S., Chemistry (with emphasis on analytical chemistry) and systems ecology, 1973
Professional Experience
  • Research Ecologist,  Forest Service, Pacific Southwest Research Station,  2010 - Current
  • Soil Scientist,  Forest Service, Pacific Southwest Research Station,  1978 - 2010
Awards & Recognition
  • Distinguished Publication Award, Pacific Southwest Research Station, 1996
    for the publication, "Riggan, P. J., F. H. Weirich, L. F. DeBano, et al. 1994. Effects of fire severity on nitrate mobilization in watersheds subject to chronic atmospheric deposition. Environmental Science and Technology 28(3): 369-375."
  • Distinguished Publication Award, Pacific Southwest Research Station, 1990
    for the publication, "Anderson, I. C., J. S. Levine, M. A. Poth, and P. J. Riggan. 1988. Enhanced biogenic emissions of nitric oxide and nitrous oxide following surface biomass burning. Journal of Geophysical Research 93(D4): 3893-3898."
  • NASA National Group Achievement Award, 1988
    for contributions towards assessment of the effects of biomass combustion on the global environment
Other Publications
Research Highlights

Measuring Prescribed Burns in Tropical Savannas

Year: 2011
A remote-sensing based model has been developed that produces heat flux estimates that are highly consistent with in situ fire plume measurements. Because carbon flux from the fires was strongly correlated with heat flux measurements, the rate of fuel consumption by the entire flaming front of a la...

Satellite-based Earth Observations Aid Fire Fighting and Fire Forecasting

Year: 2013
The Forest Service's Pacific Southwest Research Station, in association with multiple partners, has developed methods based on new sources of satellite data to provide near real-time fire mapping and measurement. These data also have been incorporated in a simulation model that includes weather fore...

Research Explains Deadly and Unexpected Fire Behavior of the 2006 Esperanza Fire in Southern California

Year: 2014
Simulations and thermal imaging of a wind-driven chaparral wildfire show the importance of fire-induced winds in the direction and velocity of fire spread that led to firefighter fatalities in the 2006 Esperanza Fire in Southern California.

Remote Sensing Tools Preemptively Detect Drought-Stressed Pines with 80% Accuracy

Year: 2020
Large swaths of dead trees across a landscape pose an extreme fire hazard, as seen in the southern Sierra Nevada range of California. Researchers developed a method that uses remote sensing and spectral sensing to pre-emptively identify drought-stressed trees. Forest managers can use this advance no...